1. Field of the Invention
The present invention relates to a horizontal linear vibrator and, more particularly, to a horizontal linear vibrator designed to be mounted on a personal mobile terminal to vibrate.
2. Description of the Related Art
In general, one of the key functions requisite for communication devices is a call reception function. Commonly used call reception functions include a sound generating function that generates a melody or a bell sound and a vibration function that transfers vibrations to a device.
Among the functions, the vibration function is commonly used so as not to interfere with others by preventing a melody or a bell sound from being transferred to the exterior through a speaker.
In order to implement such a vibration function, in general, a small vibration motor is driven to transfer a driving force to a case of a device to make the device vibrate.
In particular, recently, as mobile terminals have been reduced in size and have improved in quality, the use of a touch screen type display device has been greatly favored, requiring a vibration generation function when a touch is applied to the touch screen, so the improvement of the vibration motor has gradually taken place.
A vibration motor applied to mobile phones generates rotatory power in order to rotate a rotational part of an unbalance mass, thus obtaining mechanical vibrations, and in this case, rotatory power is generated such that it is mostly subjected to a rectifying action through a brush and a contact point of a commutator (or rectifier) to provide current to a rotor coil.
However, in the brush type structure using a commutator, when the motor rotates, the brush passes through the gap between segments of the commutator, generating a mechanical friction and an electrical spark, abrading the brush and the commutator and thereby shortening the life span of the motor.
In addition, because voltage is applied to the motor by using a moment of inertia, time is taken to reach a target amount of vibrations, so it is difficult to implement vibrations suitable for touch screen-employed personal mobile terminals and the like.
Meanwhile, a linear horizontal vibrator vibrates by using a resonance frequency and electromagnetic force. Because the linear horizontal vibrator does not cause mechanical friction or abrasion, it has a long life span and fast response time, thus being favored for a haptic feedback structure.
In this case, the resonance frequency is a key factor for determining vibration power; however, the resonance frequency varies depending on the fabrication deviation of components, which makes the vibration power vary to fail to obtain desired vibration power. Thus, techniques for resolving such problems are required.